1. Field of the Invention
The present invention relates to an image-forming device which receives an event registration request from an information-processing device and executes notification in case of generating an event, and a control method which is applied to the image-forming device.
2. Description of the Related Art
Conventionally, network devices such as a printer, a multifunction device and the like which are connected to a network and thus can be operated from a computer through the network are generally used. Here, as a means for managing the network devices from the computer, a management protocol such as an SNMP (Simple Network Management Protocol) is widely used. Thus, an administrator of the network can monitor, from his/her own computer, states of these devices on the network by using the management means such as the SNMP.
Generally, systems of monitoring in real time the states of the network devices from the host computer include two kinds of systems, that is, a polling system and an event system. In the polling system, the host computer acquires the states of the devices at certain intervals. Although it is relatively easy to implement this system in the host computer and the device, the acquisition of the state is necessary even if the state of the device does not change. For this reason, in the polling system, there is a drawback that network traffics become heavy, and is a further drawback that CPU resources of the host computer and the devices are wastefully used. On the other hand, as compared with the polling system, it is relatively complicated to implement the event system in the host computer and the device. However, in the event system, since notification to the host computer is executed only when a change occurs actually in the device, there is an advantage that unnecessary traffics or the like do not occur. In any case, since the above-described SNMP is applicable to both the polling system and the event system, the administrator can appropriately use these systems according to use environments.
Further, in recent years, standardization of web service technology has advanced, and specifications for executing event transmission/reception by using web services have been formulated gradually. The relevant specifications are called “WS-Eventing (Web Services Eventing)” and are available from the Microsoft® website.
FIG. 1 illustrates a constitution which is defined by the “WS-Eventing” specifications. In FIG. 1, a subscriber 101 transmits an event registration request (REGISTER) to an event source 102. If the event registration request is received, the event source 102 generates and holds a subscription 103 which includes event transmission destination addresses, event types and the like. Further, the event source 102 responds an identifier of the subscription and its validity duration, as a response to the event registration request. After then, if an event is generated, the event source 102 transmits a notification message (NOTIFICATION) to an event sink 104. If the subscriber 101 wishes to continuously receive the notification message after the validity duration elapsed, the subscriber 101 transmits an event renew request (RENEW) to the event source 102 before the validity duration elapse. Incidentally, the subscriber 101 and the event sink 104 may be a physically identical terminal.
According to the “WS-Eventing” specifications, for example, the computer of the administrator is used as the subscriber and the event sink and the device is used as the event source, whereby the device management to which the web service technology is applied can be achieved.
Further, Japanese Patent Application Laid-Open No. H11-312128 describes a process which is to be executed when event registration is executed from a host computer.
On the other hand, with the object of the protection of environment, low power consumption is expected even in a device. For example, Japanese Patent Application Laid-Open No. 2001-180083 proposes a mechanism of aiming at power saving not only in a printer engine but also in a controller for an image process and the like. More specifically, Japanese Patent Application Laid-Open No. 2001-180083 points out as a problem that, since an externally sent communication request is conventionally monitored by a CPU constituting the controller, the power for the CPU to be used for such monitoring is wasted. For this reason, in Japanese Patent Application Laid-Open No. 2001-180083, it is monitored always, by a communication interface (communication controller) which includes an energized reception buffer, whether or not data are received from an external host computer group, thereby interrupting power-on to the controller including the CPU. Thus, it is possible to receive an external print request.
However, in case of executing such device management by the conventional event system, there is a following problem.
That is, if the device is in a power saving state, this device returns to be in a normal state every time an event registration request is received, and again enters into the power saving state after an event registration process ended. However, in a case where plural host computers execute the respective event registration processes with respect to a single device, time when each of those computers executes the event registration process is different from others. For this reason, as the number of host computers increases, the number of times that the device changes its state between the power saving state and the normal state increases, whereby the respective parts concerning such changing operations are seriously consumed. For example, if the host computers for which the validity duration of event registration elapsed request to renew event registration, those plural host computers respectively request such renewal at random. Accordingly, the device which is in the power saving state returns to be in the normal state every time those requests are received, whereby it is inefficient in power saving. On the contrary, it is conceivable to prevent, by setting no validity duration of event registration, the requests of renewal of event registration from being sent from the host computers. However, in that case, an event notification is sent even to the computer which does not expect it (for example, a host computer of which the power source is being off, a host computer which expects an event notification only during a certain period, or the like). Accordingly, to prevent such wasteful event notification, it is desirable for the device to set validity duration of event registration.
Moreover, generally, in a case where a hard disk (HDD) is used, if a power source is once turned on, power is not interrupted for a certain period of time (hereinafter, called HDD protection duration) to prevent consumption and damage of the parts in the HDD. For this reason, with respect to the device that it is necessary to turn on the power source of the HDD in the process of requesting event registration, the time during which the power source of the HDD is being on becomes longer as the number of host computers increases. As a result, an amount of power consumption increases.